An understanding of the chemical nature of the structural proteins making up periodontal tissues is critical to an understanding of the destructive mechanisms of periodontal disease. The investigations supported by this grant are systematic efforts to advance the knowledge in this area. The initial series of experiments were designed to determine the nature and levels of the collagen types found in gingiva, cementum and periodontal ligament. It has been found that the two soft connective tissues contain both Type I and Type III collagens in ratios of about four to one. In contrast, cementum collagen is almost exclusively Type I collagen, but there is a low but detectable level of Type III collagen in this tissue. Further experiments extending these observations are underway. BIBLIOGRAPHIC REFERENCES: W. T. Butler, H. Birkedal-Hansen and R. E. Taylor, "Proteins of the Periodontium. The Chain Structure of the Collagens of Bovine Cementum and Periodontal Ligament" in Extracellular Matrix Influences on Gene Expression, edited by H.C. Slavkin, New York, Academic Press p. 371 (1975). W.T. Butler, H. Birkedal-Hansen and R.E. Taylor, "Characterization of Bovine Periodontal Ligament and Cementum Collagen" IADR Abstracts 54, 66 (1975).